Idler mechanism for magnetic tape device and tape device

ABSTRACT

An idler mechanism for a magnetic tape device. An idler gear is swingingly displaced between first and second positions to selectively transmit rotation to one of a pair of reels. One end of an arm-like swinging member is coupled in a relatively rotatable manner to a center shaft of an input gear which always meshes with the idler gear and which is rotated forwardly and reversely. A shaft which is disposed on the other end of the swinging member is inserted in a relatively rotatable manner into a bearing hole of the idler gear. A surface of a flange which is disposed on the input gear is formed as a friction force applying face which extends radially outwardly so as to be inclined downwardly. An outer peripheral portion of the idler gear slidably comes into contact with the friction force applying face.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an idler mechanism for amagnetic tape device, particularly to an idler mechanism for a magnetictape device in which an idler gear is swingingly displaced by using africtional resistance.

[0003] 2. Description of the Related Art

[0004] A tape device such as a magnetic recording and reproducing devicehas a pair of reels to which a supply tape reel and take-up tape reelhoused in a tape cassette are respectively attached. The reels rotatethe tape reels in a forward direction and a reverse direction. An idlermechanism is used for switching over the rotational direction of thereels.

[0005]FIG. 3 is a partially cutaway schematic side view of aconventional idler mechanism. In this type, an idler gear is swinginglydisplaced between a first position where rotation is transmitted to oneof reels, and a second position where rotation is transmitted to theother reel.

[0006] In FIG. 3, 1 denotes an idler gear, and 2 denotes an input gearwhich always meshes with the idler gear 1 and is rotated in forward andreverse directions. An arm-like swinging member 3 is disposed on thegears 1 and 2. One end of the swinging member 3 is coupled in arelatively rotatable manner to a center shaft 21 of the input gear 2. Ashaft hole 31 is formed in the other end of the swinging member 3. Theidler gear 1 is rotatably attached to a shaft 4 which is inserted intothe shaft hole 31. A spring 5 for urging the idler gear 1 toward theswinging member 3 is interposed between a spring bracket 41 disposed onthe shaft 4 and the idler gear 1.

[0007] In the idler mechanism, when the input gear 2 is rotated, theidler gear 1 is rotated in the direction which is opposite to therotational direction of the input gear 2. Since the idler gear 1 isurged toward the swinging member 3 by the spring 5, a frictionalresistance is generated in an overlapping region “a” between the idlergear 1 and the swinging member 3. In a meshing region “b” between theinput gear 2 and the idler gear 1, therefore, a rotational torque whichcauses the idler gear 1 to swing about the center shaft 21 of the inputgear 2 is generated. The idler gear 1 is swingingly displaced about thecenter shaft 21 by the rotational torque. When the rotational directionof the input gear 2 is switched over to the forward or reversedirection, the idler gear 1 is swingingly displaced between a firstposition where rotation is transmitted to one of reels, and a secondposition where rotation is transmitted to the other reel.

[0008] JP-A-57-100646 discloses an idler mechanism shown in FIGS. 4 and5. An idler gear is swingingly displaced between first and secondpositions without using the spring 5 shown in FIG. 3.

[0009] The idler mechanism shown in FIGS. 4 and 5 is used for drivingreels of a tape recorder. A center portion of a support lever 93 iscoupled in a relatively rotatable manner to a capstan shaft 90 to whicha capstan gear 91 is fixed. A pair of idler gears 94 and 95, whichalways mesh with the capstan gear 91, are rotatably supported by shafts96 and 97 that are attached to both ends of the support lever 93respectively. The lower ends of the shafts 96 and 97 are placed on theupper face of a flywheel 98 which is fixed to the capstan shaft 90.

[0010] When the capstan gear 91 is rotated, the capstan shaft 90 and theflywheel 98 are rotated together, and hence the shafts 96 and 97 whichare placed on the upper face of the flywheel 98 are displaced togetherwith the idler gears 94 and 95 about the capstan shaft 90 by theflywheel 98. When the rotational direction of the capstan gear 91 isswitched over to the forward or reverse direction, the idler gears 94and 95 are swingingly displaced between a first position where rotationis transmitted to one of reels, and a second position where rotation istransmitted to the other reel. In the first position, the idler gear 94meshes with a reel gear 92 which rotates the one reel 92 a. In thesecond position, the idler gear 95 meshes with a reel gear 99 whichrotates the other reel 99 a.

[0011] In the conventional structure described with reference to FIG. 3,a frictional resistance is generated by urging the idler gear 1 towardthe swinging member 3 by the spring 5, and a rotational torque whichcauses the idler gear 1 to swing is generated by the frictionalresistance. Therefore, the spring 5 is inevitably used for swinginglydisplacing the idler gear 1 between the first and second positions. Thiscauses problems in that the number of parts is increased, that theassembly process becomes cumbersome, and that the cost is raised. Asshown in FIG. 3, the shaft 4 is additionally required for attaching theidler gear 1 and the swinging member 3, thereby causing a furtherproblem in that the cost is correspondingly increased.

[0012] By contrast, in the configuration described with reference toFIGS. 4 and 5, no spring is used, and hence the number of parts can becorrespondingly reduced. In the configuration, however, under the statewhere the idler gears are located in the first or second position tomesh with the reel gear 92 or 99, the upper face of the flywheel 98 rubswith the lower ends of the shafts 96 and 97 because the shafts 96 and 97are held to given positions but the flywheel 98 is rotated together withthe capstan shaft 90. Therefore, the lower ends of the shafts 96 and 97,or the upper face of the flywheel 98 easily wears, and there arises thepossibility that the performance stability of the idler mechanism isimpaired by the wear.

SUMMARY OF THE INVENTION

[0013] It is an object of the present invention to provide an idlermechanism for a magnetic tape device in which the spring described withreference to FIG. 3 is not required.

[0014] It is another object of the present invention to provide an idlermechanism for a magnetic tape device in which an initial performancestability can be maintained for a long time period.

[0015] It is a further object of the present invention to provide anidler mechanism for a magnetic tape device in which not only the spring,but also the shaft used for coupling the swinging member with the idlergear described with reference to FIG. 3, are not required.

[0016] According to an aspect of the present invention, there isprovided an idler mechanism for a magnetic tape device in which an idlergear is swingingly displaced between first and second positions toselectively transmit rotation to one of a pair of reels, wherein aswinging member is coupled in a relatively rotatable manner to the idlergear, and also to an input gear which always meshes with the idler gearand which is rotated forwardly and reversely, a friction force applyingface is concentrically formed on one of the idler gear and the inputgear, and the other one of the idler gear and the input gear slidablycomes into contact with the friction force applying face.

[0017] According to the configuration, the friction force applying faceis concentrically formed on one of the input gear and the idler gearwhich always mesh with each other, and the other one of the gearsslidably comes into contact with the friction force applying face, sothat a rotational torque of the idler gear is generated by a frictionalresistance of the contacting part. Therefore, it is not required to usethe spring described with reference to FIG. 3.

[0018] Preferably, the friction force applying face is formed by asurface of a flange which is integrally formed on the one gear, and anouter peripheral portion of the other gear slidably comes into contactwith the friction force applying face. According to the configuration,it is not required to use the flywheel described with reference to FIG.5, and hence the number of parts is reduced.

[0019] Preferably, the surface of the flange extends radially outwardlyso as to be inclined downwardly. According to the configuration, thefriction force applying face which is formed by the outward and downwardinclined surface of the flange comes into point contact or line contactwith the outer peripheral portion of the gear. Therefore, a situation inwhich the frictional resistance of the contacting part is undulyincreased and an excessively large load is applied to the input geardoes not occur.

[0020] Preferably, the swinging member comprises a shaft which isinserted in a relatively rotatable manner into a bearing hole that isformed in the other gear, the one gear comprises a flange projectingfrom a periphery thereof, and the other gear is held in a space betweenthe friction force applying face formed by the surface of the flange andthe swinging member. According to the configuration, it is possible touse the shaft of the swinging member instead of the shaft memberdescribed with reference to FIG. 3, and hence the shaft member is notnecessary. Thus, the number of parts is decreased. Since the idler gearis held in the space between the friction force applying face and theswinging member, it is not necessary to provide the shaft with a portionfor preventing the idler gear from slipping off. This is useful forsimplifying the shapes of the shaft and the swinging member having theshaft to suppress the production cost.

[0021] According to an aspect of the present invention, there isprovided an idler mechanism for a magnetic tape device in which an idlergear is swingingly displaced between first and second positions toselectively transmit rotation to one of a pair of reels, one end of anarm-like swinging member is coupled in a relatively rotatable manner toa center shaft of an input gear which always meshes with the idler gearand which is rotated forwardly and reversely, a shaft which isintegrally disposed on the other end of the swinging member is insertedin a relatively rotatable manner into a bearing hole that is formed inthe idler gear, a friction force applying face which extends radiallyoutwardly so as to be inclined downwardly is formed by a surface of aflange which is formed on the input gear to project from a periphery ofthe input gear, and an outer peripheral portion of the idler gear thatis held in a space between the friction force applying face and theswinging member slidably comes into contact with the friction forceapplying face in a part where the input gear meshes with the idler gear.

[0022] According to the configuration, the outer peripheral portion ofthe idler gear which is placed in the first or second position comesinto contact with the friction force applying face of the input gear inthe part where the idler gear meshes with the input gear. Therefore, astate is obtained in which the outer peripheral portion of the idlergear that is rotated in the same direction as the friction forceapplying face is in contact with the friction force applying face thatis rotated together with the input gear. Consequently, the degree ofrubbing between the friction force applying face and the outerperipheral portion of the idler gear is lower than that obtained in thesituation described with reference to FIG. 5, i.e., in the case wherethe upper face of the rotated flywheel 98 rubs with the shafts 96 and 97that are stopped. Thus, wear does not occur. Moreover, rotation of thefriction force applying face is transmitted to the idler gear.Therefore, there arises a further advantage that the rotational torqueof the input gear which is required for rotating the idler gear can bereduced. Other functions will become apparent from preferred embodimentsdescribed below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a plan view showing a configuration of a magnetic tapedevice in which an idler mechanism of the invention is used;

[0024]FIG. 2 is a partially cutaway enlarged side view of the idlermechanism, looking from a line II-II of FIG. 1;

[0025]FIG. 3 is a partially cutaway side view of a conventional idlermechanism;

[0026]FIG. 4 is a plan view of a prior art;

[0027]FIG. 5 is a front view of the prior art;

[0028]FIG. 6 is a partially cutaway enlarged side view of a secondembodiment;

[0029]FIG. 7 is a partially cutaway enlarged side view of a thirdembodiment;

[0030]FIG. 8 shows a variation of the first embodiment; and

[0031]FIG. 9 shows a variation of the second embodiment.

DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENTS

[0032]FIG. 1 is a diagram showing the configuration of main portions ofa magnetic tape device in which an idler mechanism 6 of a firstembodiment of the invention is used. FIG. 2 is a partially cutawayenlarged side view of the idler mechanism 6, looking from a line II-IIof FIG. 1.

[0033] Referring to FIG. 1, 81 and 82 denote reels. Gears 83 and 84 aredisposed concentrically on the reels 81 and 82, respectively. The idlermechanism 6 is interposed between one of the gears, i.e., the gear 83,and a gear train 85. The gear train 85 meshes with the other gear, i.e.,the gear 84. When an idler gear 61 of the idler mechanism 6 is locatedin a first position where the idler gear meshes with the one gear 83 asindicated by the solid line, rotation of the idler gear 61 istransmitted to the reel 81 via the gear 83. When the idler gear 61 ofthe idler mechanism 6 is located in a second position where the idlergear meshes with a gear of the gear train 85 as indicated by the phantomline, rotation of the idler gear 61 is transmitted to the reel 82 viathe gear train 85 and the gear 84.

[0034] As shown in FIG. 1 or 2, an input gear 62 always meshes with theidler gear 61. When the input gear 62 is rotated forwardly or reversely,the idler gear 61 is rotated in the direction which is opposite to therotational direction of the input gear 62. A center shaft 63 of theinput gear 62 is fitted into a hole 65 which is formed in one end of anarm-like swinging member 64 in a relatively rotatable manner. A shaft 66which protrudes downward is integrally formed on the other end of theswinging member 64 by a synthetic resin. The shaft 66 is inserted into abearing hole 67 of the idler gear 61 in a relatively rotatable manner.As seen from FIG. 2, the shaft 66 is formed into a rod-like shape inwhich the diameter is uniform over the whole range in the axialdirection.

[0035] A flange 68 is disposed on the lower end of the input gear 62.The flange is molded integrally with the input gear 62 and projects fromthe periphery of the input gear 62. A surface of the flange 68 is formedas a friction force applying face 69 which extends radially outwardly soas to be inclined downwardly. In one part in the circumferentialdirection of the friction force applying face 69, specifically, ameshing part “c” between the input gear and the idler gear, a lower endcorner part of the outer peripheral portion of the idler gear 61 comesinto contact with the friction force applying face 69. Therefore, theidler gear 61 is held in a space between the friction force applyingface 69 of the input gear 62 and the swinging member 64. In this state,the flange 68 prevents the idler gear 61 from slipping off from theshaft 66. Consequently, the shaft 66 can be formed into a rod-like shapein which the diameter is uniform over the whole range in the axialdirection, as described above.

[0036] In this embodiment, when the input gear 62 is rotated, the idlergear 61 is rotated in the direction which is opposite to the rotationaldirection of the input gear 62. Since the lower end corner of the outerperipheral portion of the idler gear 61 is in contact with the frictionforce applying face 69 of the input gear 62, a rotational torque forswinging the idler gear 61 between the first and second positions isgenerated by the frictional resistance generated in the contacting part.Therefore, the idler gear 61 is swingingly displaced about the centershaft 63 of the input gear 62 by the rotational torque. When therotational direction of the input gear 62 is switched over to theforward or reverse direction, the idler gear 61 is swingingly displacedbetween the first position where the idler gear meshes with the gear 83to transmit rotation to the one reel 81, and the second position wherethe idler gear meshes with the gear train 85 to transmit rotation to theother reel 82.

[0037] The lower end corner of the outer peripheral portion of the idlergear 61 which is located in the first or second position comes intopoint contact or line contact with the friction force applying face 69of the input gear 62, in the meshing part “c” between the idler gear 61and the input gear 62. Therefore, a situation in which the frictionalresistance of the contacting part is unduly increased and an excessivelylarge board is applied to the input gear 62 does not occur. Moreover,the rubbing between the friction force applying face 69 which is rotatedtogether with the input gear 62, and the lower end corner of the outerperipheral portion of the idler gear 61 which is rotated in the samedirection as the face is reduced, so that wear does not occur in thefriction force applying face and the idler gear 61. This function willbe enhanced by applying grease to at least one of the friction forceapplying face and the idler gear 61. Since rotation of the frictionforce applying face 69 is transmitted to the idler gear 61, there arisesa further advantage that the rotational torque of the input gear 62which is required for rotating the idler gear 61 via the meshing part“c” can be reduced.

[0038] In the above embodiment, the flange 68 having the friction forceapplying face 69 is disposed on the input gear 62. This configurationmay be modified in the following manner. A flange having a frictionforce applying face may be disposed on the idler gear, and the inputgear may slidably come into contact with the friction force applyingface.

[0039]FIG. 6 shows a second embodiment of the present invention. Aninput gear 62 always meshes with an idler gear 71. When the input gear62 is rotated forwardly or reversely, the idler gear 71 is rotated inthe direction which is opposite to the rotational direction of the inputgear 62. The structure of the input gear 62 is same as that of the firstembodiment. A center shaft 63 of the input gear 62 is fitted into a hole65 which is formed in one end of an arm-like swinging member 74 in arelatively rotatable manner. A shaft 76 which protrudes downward isintegrally formed on the other end of the swinging member 74 by asynthetic resin. The shaft 76 is inserted into a bearing hole 77 of theidler gear 71 in a relatively rotatable manner. The shaft 66 is formedinto a rod-like shape in which the diameter is uniform over the wholerange in the axial direction.

[0040] In one part in the circumferential direction of the frictionforce applying face 69, specifically, a meshing part “c” between theinput gear and the idler gear, a lower end corner part of the outerperipheral portion of the idler gear 71 comes into contact with thefriction force applying face 69. In this state, a gap “G” is definedbetween an upper face of the idler gear 71 and a lower face of theswinging member 74.

[0041] A circumferential groove 78 is formed on the upper face of theidler gear 71. The circumferential groove 78 is concentric with thebearing hole 77 and surrounds the bearing hole 77.

[0042] A cylinder-like guide wall 74 a is disposed on the lower face ofthe swinging member 74. One side face of the circumferential groove 78and the guide wall 74 a is engaging in a relatively rotatable manner. Inthis embodiment, an inner circumferential side face of thecircumferential groove 78 and an inner circumferential face of the guidewall 74 a is engaging in a relatively rotatable manner, with a lubricantsuch as grease is applied therebetween. Since a shearing resistanceforce of the grease is high, the swinging member 74 is surely swung.

[0043]FIG. 7 shows a third embodiment of the present invention. In thisembodiment, the shaft 76 described with reference to FIG. 6 is notdisposed on a swinging member 74. Also, the bearing hole 77 describedwith reference to FIG. 6 is not formed in an idler gear 71. An innercircumferential side face of a circumferential groove 78 and an innercircumferential face of a guide wall 74 a is engaging in a relativelyrotatable manner, with a lubricant such as grease is appliedtherebetween.

[0044] The present invention is not limited to as herein described. Inthe first embodiment, the friction force applying face 69 is formed tobe inclined downwardly. As shown in FIG. 8, a friction force applyingface 69 may be formed as a flat face which extends in a horizontaldirection. A projection 61 a is formed on a lower corner part of theidler gear 61 so as to come into point contact or line contact with thefriction force applying face 69.

[0045] In the second embodiment, the friction force applying face 69 isformed to be inclined downwardly. As shown in FIG. 9, a flange 68 mayhave a flat upper face which extends in a horizontal direction. Aprojection 69 a is formed on the upper face of the flange 68 so as tocome into point contact or line contact with a lower face of the idlergear 71.

[0046] As described above, according to the invention, the number ofparts can be reduced by eliminating the necessity of the spring and theshaft described with reference to FIG. 3. Hence, cost reduction due tothe reduced number of parts can be easily realized. Moreover, wear inthe contacting part between the friction force applying face and theinput gear or the idler gear can be suppressed. Therefore, a magnetictape device having the idler mechanism that maintains the initialperformance stability for a long time period and preventing troublessuch as disturbance of an image or skipping of sound from occurring canbe produced economically and easily.

What is claimed is:
 1. An idler mechanism for a magnetic tape device,comprising: a pair of reels; an idler gear swingingly displaced betweenfirst and second positions to selectively transmit rotation to one ofthe pair of reels, the idler gear having a bearing hole; an input gearmeshing with the idler gear, the input gear having a center shaft thatis rotated forwardly and reversely and a flange projecting from aperiphery of the input gear; an arm-like swinging member having one endcoupled in a relatively rotatable manner to the center shaft, theswinging member having a shaft integrally formed with the swingingmember on the other end and being inserted in a relatively rotatablemanner into the bearing hole; wherein a surface of the flange is formedinto a friction force applying face that extends radially outwardly soas to be inclined downwardly, and an outer peripheral portion of theidler gear that is held in a space between the friction force applyingface and the swinging member slidably comes into contact with thefriction force applying face in a part where the input gear meshes withthe idler gear.
 2. An idler mechanism for a magnetic tape device,comprising: a pair of reels; an idler gear swingingly displaced betweenfirst and second positions to selectively transmit rotation to one ofthe pair of reels; an input gear meshing with the idler gear and rotatedforwardly and reversely; a swinging member coupled in a relativelyrotatable manner to the idler gear and the input gear; and a frictionforce applying face concentrically formed on one of the idler gear andthe input gear, wherein the other of the idler gear and the input gearslidably comes into contact with the friction force applying face.
 3. Anidler mechanism for a magnetic tape device according to claim 2, whereinthe friction force applying face is formed by a surface of a flange thatis integrally formed on the one gear, and an outer peripheral portion ofthe other gear slidably comes into contact with the friction forceapplying face.
 4. An idler mechanism for a magnetic tape deviceaccording to claim 3, wherein the surface of the flange extends radiallyoutwardly so as to be inclined downwardly.
 5. An idler mechanism for amagnetic tape device according to claim 3, wherein the other gearcomprises a bearing hole, the swinging member comprises a shaft which isinserted in a relatively rotatable manner into the bearing hole, theflange is projecting from a periphery of the one gear, and the othergear is held in a space between the friction force applying face and theswinging member.
 6. An idler mechanism for a magnetic tape deviceaccording to claim 4, wherein the other gear comprises a bearing hole,the swinging member comprises a shaft which is inserted in a relativelyrotatable manner into the bearing hole, the flange is projecting from aperiphery of the one gear, and the other gear is held in a space betweenthe friction force applying face and the swinging member.
 7. An idlermechanism for a magnetic tape device according to claim 2, wherein thefriction force applying face is formed by a surface of a flange that isintegrally formed on the one gear, and an outer peripheral portion ofthe other gear has a projection that slidably comes into contact withthe friction force applying face.
 8. An idler mechanism for a magnetictape device according to claim 2, wherein a flange is integrally formedon the one gear, the friction force applying face is formed by aprojection formed on an upper face of the flange, and an outerperipheral portion of the other gear slidably comes into contact withthe friction force applying face.
 9. A tape device comprising: a pair ofreels; an idler gear swingingly displaced between first and secondpositions to selectively transmit rotation to one of the pair of reels;an input gear meshing with the idler gear and rotated forwardly andreversely; a swinging member coupled in a relatively rotatable manner tothe idler gear and the input gear; and a friction force applying faceconcentrically formed on one of the idler gear and the input gear,wherein the other of the idler gear and the input gear slidably comesinto contact with the friction force applying face.